1. Technical Field of the Invention
The present invention relates to a biaxial type of starter for starting internal combustion engines, and in particular, to such a starter in which the operative shaft of an electromagnetic switch and the armature shaft of a motor are disposed parallel to each other.
2. Related Art
Japanese Patent No. 3478211, for example, discloses a starter including: a main contact which is provided in a motor circuit for supplying current from batteries to the armature of the motor; and an electromagnetic switch for opening/closing the main contact.
The main contact consists of a B (i.e., battery)-fixed-contact connected to a high-potential side (battery side) of the motor circuit via a B-terminal bolt, an M-fixed-contact connected to a low-potential side (motor side) of the motor circuit via an M (i.e., motor)-terminal bolt, and a movable contact configured to move over against the B-fixed contact and the M-fixed contact. The movable contact comes into contact with both of the fixed contacts to make both of the fixed contacts electrically conductive and to thereby close the main contact. When both of the fixed contacts are apart from the movable contact and the electrical conduction is interrupted between these fixed contacts, the main contact is opened.
However, starters of the type mentioned above use a number of parts on the low-potential side of the motor circuit. In particular, other than the M-fixed contact, such a type of starter needs, for example, an M-terminal bolt to be fixed to an insulating contact cover of the electromagnetic switch, a sealing member (e.g., O-ring) for sealing a gap between the M-terminal bolt and the contact cover, a washer for fixing the M-terminal bolt to the contact cover, motor leads drawn from the side of the motor, and nuts for fixing the terminals of the respective motor leads to the M-terminal bolt. In this way, the number of parts is increased and thus the number of assembling processes is increased, producing factors of high cost.
In addition, since two terminal bolts (B- and M-terminal bolts) are radially juxtaposed in the electromagnetic switch, an insulation distance (creepage distance) is required to be ensured between the two terminal bolts. Under such conditions, there is a limitation in radially closely arranging the two terminal bolts, and this has prevented the downsizing (radial reduction) of such an electromagnetic switch.